Research Article Sonochemical Approach to Synthesis of Co ...downloads.hindawi.com/journals/jchem/2014/185957.pdf · the chemical structure of cobalt borides has been reported unclear

Research ArticleSonochemical Approach to Synthesis of Co-B Catalysts andHydrolysis of Alkaline NaBH4 Solutions

Bilge CoGkuner Aysel Kantuumlrk Figen and Sabriye PiGkin

Department of Chemical Engineering Yildiz Technical University 34210 Istanbul Turkey

Correspondence should be addressed to Aysel Kanturk Figen ayselkanturkgmailcom

Received 9 March 2014 Accepted 16 May 2014 Published 11 June 2014

Academic Editor Nurettin Sahiner

Copyright copy 2014 Bilge Coskuner et alThis is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Co-B catalysts are promising candidates for hydrogen evolution via hydrolysis of alkaline sodium borohydride (NaBH4) solutions

In the present paper a sonochemical approach was investigated for synthesis of Co-B catalysts and hydrolysis of alkaline NaBH4

solutions Sonochemical application on synthesizing process improved the intrinsic and extrinsic properties of Co-B catalysts suchas crystal spectral surface area pore volume pore diameter and particle size Co-B catalysts prepared by sonochemical approachpossessed smaller particle size higher surface area and higher pore volume than the Co-B catalysts prepared by coprecipitationsynthesis The effects of sonochemical process on hydrolysis of alkaline NaBH

4solutions were investigated by Arrhenius theory It

was clearly demonstrated that the advantages of alkaline NaBH4solution sonohydrolysis provide superficial effects on hydrogen

evolution kinetic as maximum H2generation rate (HGR) and minimum activation energy (119864

119886)

1 Introduction

NaBH4as a solid state hydrogen storagematerial for on-board

hydrogen generation systems has drawn much attention dueto its superficial properties as it is non-flable nontoxic selec-tive environmentally friendly and also one of the light weightcomplex hydrides with high hydrogen capacity (11 wt) [1ndash3]

NaBH4is self-decomposable in aqueous solutions and

can be stabilized by alkalization [2 4] Hydrogen generationfrom NaBH

4is supplied for fuel cells by means of alkaline

solution hydrolysis in contact with certain catalysts Severalresearchers have been focused on homogeneous andorheterogeneous catalysts such as acidsmetal complexesmetalsalts metal alloys and supported catalysts Nonnoble metalsespecially have attracted significant attention in turns of bothreactivity and costs Among different nonnoble catalysts suchas Co Ni Cu and Fe catalysts could be used for hydrolysisreactions of alkaline NaBH

4solutions from the view point of

low cost stability crystallinity and high activity [4ndash8]Between all nonnoble metals for hydrogen evolution via

hydrolysis of alkaline NaBH4solutions researchers have

shownmuch attention toCo-B catalysts because of their priorproperties Cavaliere et al stated that Co-B catalyst a black

solid could be classified in two categories as cobalt boride(Co119909B) and cobalt-boron alloy (Co-B) Considering this

the chemical structure of cobalt borides has been reportedunclear and obtained variety of structure as CoB Co

2B

Co3B and Co

119909B [9 10] Researchers suggested that XRD and

XPS techniques can be used to characterize Co-B structureFurthermore amorphous Co-B catalyst is identified with abroad peak centered at around 45∘ diffraction angle [11]Many methods for synthesizing of Co-B catalysts includingchemical reduction [12] sol-gel [13 14] and wet impregna-tion [15] are reported in the literature

Sonochemical approach has been performed in a largenumber of organic reactions Sonowaves that is to sayultrasonic irradiation are oscillating sound pressure waveswith a frequency from about 20 to 100MHz [16]Thismethodhas beenwidely used in the preparation of chemical materialssuch as ceramics [17] alloys [18] composites [19] andpolymers [20] due to its cavitation effect on chemical processSonowaves enhance the chemical reaction and mass transfervia the physicochemical changes in processed medium [2122] In addition to this sonowaves are proven as useful tech-nique for inhibiting particle agglomeration in chemical envi-ronments [23]The activity of catalysts can improve bymeansof using of sonowaves in catalysts preparation step [24]

Hindawi Publishing CorporationJournal of ChemistryVolume 2014 Article ID 185957 9 pageshttpdxdoiorg1011552014185957

2 Journal of Chemistry

Ultrasonicator

Magnetic stirringTemperature

controller

(a)

Cooling jacket

Stand

Watercirculation

H2 gas

Thermocouple

Injector

Ultrasonicator

Catalystsolution

Magnetic stirring

Peristaltic pump

NaBH4

(b)

Figure 1 Experimental systems (a) Coprecipitation and sono-coprecipitation synthesis system of Co-B catalyst (b) Alkaline NaBH4

sonohydrolysishydrolysis system

It has been reported that uniform spherical Co-B amorphousalloys were prepared by ultrasound assisted (50W) reductionof Co(NH

3)6

2+ with BH4

minus in aqueous solution in 30minIt is also noted that extremely extensive power or very longtime is harmful for activity and selectivity due to melting[23] Vanadium phosphorous oxide catalyst is synthesizedusing ultrasound irradiation in a relatively short time and itsactivity improved for hydrocarbon oxidation is tested [22]Uniform Ni-B amorphous alloy nanoparticles are preparedby ultrasound-assisted reduction of Ni(NH

3)6

2+ with BH4

minus

in aqueous solution and the particle size is controlled byadjusting the ultrasound power The unique characters ofamorphous alloy morphologic structure and Ni active siteswith higher electron density of this catalyst are crucial forits superior catalytic properties [25] Ultrasonic hydrolysis ofammonia borane (NH

3BH3) with sol-gel synthesized Co-B

catalyst is firstly investigated and it is noted that hydrogengeneration rate has been increased by 3779under ultrasonicconditions [26]

The aim of this study was to provide a sonochemicalapproach and investigation of effects on synthesizing of Co-B catalysts and hydrolysis of alkaline NaBH

4solutions For

confirming this Co-B catalysts were synthesized by twomethods as sono-coprecipitation and coprecipitation fromcobalt(II) chloride hexahydride (CoCl

2sdot6H2O) and boron

oxide (B2O3) and hydrolysis of alkaline NaBH

4solutions

were performed under sonowaves and magnetic stirringThe intrinsic and extrinsic properties of Co-B catalystswere discussed based on Brunauer-Emmett-Teller surfaceanalysis (BET) X-ray diffraction (XRD) Fourier transforminfrared spectroscopy (FT-IR) and scanning electron spec-troscopy (SEM) characterizations The hydrolysis of alkaline012MNaBH

4solutions were investigated under different

reaction temperatures (22∘Cndash60∘C) in presence of Co-Bcatalysts under two different conditions For identifying theeffect of sonochemical approach on hydrolysis kinetics of

alkaline NaBH4solutions Arrhenius theory was used to

determine the kinetic parameters

2 Materials and Methods

B2O3(99 purity) was supplied from Eti Mine Works

General Management-Turkey CoCl2sdot6H2O with 97 purity

used as cobalt source was purchased from Merck Sodiumhydroxide (NaOH) was purchased from Labor Technic usedas stabilizer for NaBH

4solutions NaBH

4with a minimum

purity of 96 was supplied by Fluka

21 Sonochemical Approach to Coprecipitation Synthesis ofCo-B Catalyst The system for synthesizing the Co-B cat-alysts was illustrated in Figure 1(a) In synthesis of Co-Bcatalysts two different methods were used For sonochemicalapproach reactor modified with ultrasonicator was used incoprecipitation synthesis of Co-B catalyst The laboratorytype ultrasonicator that was commonly used for cleaningpurpose was selected The ultrasonic power of the bath-typeultrasonicator (Bandelin Sonorex Super RK 255H) is 280Wand frequency of irradiation is 35 kHz Self-certificationof sono-co-precipitation synthesis which was provided bycoprecipitation synthesis of Co-B catalyst via reactor modi-fied with magnetic stirring system was used

In synthesis of Co-B catalysts firstly 05M B2O3solution

was prepared and then CoCl2sdot6H2O were added 01M

NH4OH was added by drop wise method until pH level of

solution reached 6 The solution was mixed for 2 hours at85 plusmn 3

∘C in reactor to obtain bulk structure According to theprocedure ultrasonicator or magnetic stirring (500 rpm) wasapplied during the Co-B catalyst synthesis reaction

In the synthesis of Co-B catalysts cobalt precious-CoCl2

and boron source-B2O3were solved into water CoCl

2sep-

arates into its anions and cations by the effect of 01M

Journal of Chemistry 3

Table 1 Texture properties of Co-B catalysts

Code Synthesis type Specific surface area (m2g) Pore size (cm3g) Pore volume (A)CoB-1 sono-coprecipitation 336 plusmn 016 00141 16867CoB-2 Coprecipitation 198 plusmn 011 00066 13339

NH4OH addition the synthesis reaction occurred as (1) The

coprecipitation synthesis reaction of Co-B compounds aregiven as below

9Co2+ + 2B2O3

Alkali medium997888997888997888997888997888997888997888997888997888997888rarr 2Co

3B + Co

3(BO3)2 (1)

Subsequently bulk materials were dried at approximately100∘C under the vacuum condition for overnight to eliminatethe remaining water molecules Moreover forming stablestructure catalysts were calcined at 500∘C for 4 hours in airAs a last step Co-B catalysts were prepared for characteriza-tion of the intrinsic and extrinsic properties

XRD patterns of Co-B catalysts were recorded usingPhilips Panalytical XrsquoPert-Pro diffractometer with Cu K120572radiation in a range of diffraction angles from 5∘ to 80∘ withCu K120572 radiation (120582 = 015418mm) at operating parametersof 40mA and 45 kV with 002∘ step size and speed of 1∘minThe morphology and particular size of the Co-B catalystswere observed by using SEM techniques (JEOL JSM 5410LV) The catalysts were covered with Au and made readyfor analysis by fixing to the devicersquos sample holder withthe help of a carbon sticky band Surface properties of Co-B catalysts were determined via using a surface area andporosimetry analyzer (Micromeritics ASAP 2020) Spectralproperties were characterized via FT-IR (Perkin Elmer Spec-trum One) with ATR accessories in the spectral range of4000 cmminus1ndash650 cmminus1 with a spectral resolution of 4 cmminus1 inthe transmittance mode

22 Sonochemical Approach to Hydrolysis of Alkaline NaBH4

Solutions The hydrolysis reaction of NaBH4is as given

below Four mole H2is generated during efficient hydrolysis

reaction per mole NaBH4[1ndash3]

NaBH4+ 2H2O 997888rarr NaBO

2+ 4H2 (2)

Figure 1(b) shows the systems the hydrolysis reactions ofalkaline NaBH

4solutions were carried out The 15mL glass

reactor was immersed in a system and connected to thewater filled inverter burette in order to measure the evolvedhydrogen volume The measured data was used in inves-tigation of hydrolysis kinetic To compare the results ofsonochemical hydrolysis the systemmodified with magneticstirrer and the same procedure was followed for magneticstirring (500 rpm) According to the procedure ultrasonica-tor or magnetic stirring was applied during the hydrolysis ofalkaline NaBH

4solutions

In the experiments 10 wt NaOH alkaline 012MNaBH

4was hydrolyzed in presence of 05mg catalysts The

reactions applied in range of 22∘Cndash60∘C with temperaturecontrolling system

The kinetic investigation of sonochemical and magneticstirring hydrolysis of alkaline NaBH

4solution was identified

via Arrhenius theory The characterization of hydrolysisreaction behavior was enlightened by zero-order first-orderand second-order reaction kinetic models The activationenergies and rate constants were determined via Arrheniustheory [12 26 27]

In literature zero-order reaction is shown as belowmodelgenerally defined as reactant independent kinetic modelIn the model 119862NaBH

4

is the concentration 119903 is the rate ofreaction and 119896 is the reaction rate constant based on thesolution volume

119889119862NaBH4

119889119905= minus119903NaBH

4

= minus119896 (119879) (3)

Equation (3) is formed as below when the integration isapplied

(119862NaBH40

minus 119862NaBH4

) = minus119896 (119879) sdot 119905 (4)

First-order reaction model is dependent on the reactantsrsquoconcentration and its basic (5) and integration applied forms(6) are shown below

119889119862NaBH4

119889119905= minus119903NaBH

4

= minus119896 (119879) sdot 119862NaBH4

(5)

ln(119862NaBH

40

119862NaBH4

) = 119896 (119879) sdot 119905 (6)

The second-order reaction model is also dependent onreactants concentration with second degree and integratedforms are shown below

119889119862NaBH4

119889119905= minus119903NaBH

4

= minus119896 (119879) sdot 1198622

NaBH4

(7)

(1

119862NaBH4

minus1

119862NaBH40

) = minus119896 (119879) sdot 119905 (8)

3 Results and Discussion

31 Sonochemical Approach to Coprecipitation Synthesis of Co-B Catalyst Co-B catalysts were synthesized via two differentsystems (Figure 1(a)) The CoB-1 catalyst was synthesizedwith sonochemical approach and CoB-2 which used as con-trol sample was synthesized bymagnetic stirring systemThecatalysts were codded according to their synthesis methods(Table 1)

Table 1 shows the textural properties of Co-B catalystsComparing the specific surface areas of CoB-1 catalyst withCoB-2 catalyst the sonochemical approach a considerablyincreased the surface area of catalyst up to 70 With thismethod not only specific surface area increased but also other

4 Journal of Chemistry

(a)

(b)

Figure 2 The SEM images of Co-B catalysts with times1000 (left) and times5000 (right) magnification (a) CoB-1 catalyst (b) CoB-2 catalyst

Table 2 Particle size distribution of Co-B catalysts

CodeAverage particle

size(120583m)

Maximumparticle size

(120583m)

Minimumparticle size

(120583m)CoB-1 125 277 030CoB-2 300 739 057

texture properties as pore size and volume of catalysts wereimproved up to 114 and 26 respectively

Figure 2 shows the SEM images of Co-B catalysts at1000 and 5000 magnification Particles of Co-B catalystsynthesized by sonochemical approach were homogeneouslydispersed and smaller than coprecipitation synthesized Co-Bcatalyst

Table 2 shows average minimum andmaximum particlesizes were measured from SEM images It was indicated thatCo-B prepared with sonochemical coprecipitation synthesiswas shown a smaller average size of 125 120583m and particle sizeof the catalyst was reduced up to 58 (Table 2) BET resultswere consistent with the SEM results

Figure 3 shows XRD patterns of synthesized Co-B cata-lysts Comparing XRD pattern of synthesized catalysts withthe standard diffraction spectrum (JCPDS 00-012-0443 and01-073-1540) the synthesized product was crystalline Co

3B

and Co3(BO3)2 The sharpness of XRD reflections clearly

050

100150200250300350

5 17 29 41 53 65 77 89

Cou

nts

CoB-1CoB-2

JPCDS 00-012-0443JPCDS 01-073-1540

ΔΔΔ

lowast

lowastlowastlowastlowastlowast

ΔΔ

ΔΔ

Δ

Δ

ΔΔ Δ

ΔΔ

Δ ΔΔΔΔ

Δ

lowast

2120579 (∘)

CoB3

Co3(BO3)2

Figure 3 The XRD patterns of Co-B catalysts

shows that the synthesized Co-B catalysts were highly crys-talline The characteristic peaks of phases were indexed inXRD patterns It was clear that sonochemical treatment doesnot affect the crystalline phases of Co-B catalysts

Figure 4 shows FT-IR spectrums of Co-B catalysts In adirect comparison of the observed FT-IR spectrums of bothcatalysts it was clearly seen that B-O band frequencies weredetected at the same wave number regions The bands at3197 cmminus1 and 3206 cmminus1 corresponded to vibration of H-O groups The bands at 1403 cmminus1 and 1350ndash935 cmminus1 werecontributed asymmetric stretching of B-O The bands were

Journal of Chemistry 5

0

20

40

60

80

100

120

650 1150 1650 2150 2650 3150 3650Wavenumber

CoB-2CoB-1

T(

)

(cmminus1)

Figure 4 The FT-IR spectrum of Co-B catalysts

0

20

40

60

80

0 5 10 15

Gen

erat

ed H

2vo

lum

e (m

L)

Time (min)

Alkaline sonohydrolysis

40∘C

60∘C

80∘C

NaBH4

(a)

Gen

erat

ed H

2vo

lum

e (m

L)

0

20

40

60

80

0 5 10 15 20Time (min)

Alkaline magnetic stirring hydrolysis

22∘C

40∘C

60∘C

NaBH4

(b)

Figure 5 Hydrogen generation volume versus time for sonohydrolysis and magnetic stirring hydrolysis of alkaline (10wt) 012 NaBH4

solutions in presence of 05mg CoB-1 catalyst

assigned between 950ndash870 cmminus1 and 710ndash795 cmminus1 and weresymmetric stretching band of B-O [28ndash30]

CoB-1 catalysts prepared via sonochemical coprecipita-tion synthesis show the best intrinsic and extrinsic propertiesthat are contributing factors to the catalytic activity Itwas concluded to start sonohydrolysis of alkaline NaBH

4

solutions with CoB-1 catalysts which were prepared viasonochemical coprecipitation synthesis

32 Sonochemical Approach to Hydrolysis of Alkaline NaBH4

Solutions In order to investigate the effect of sonochemicalapproach hydrolysis of alkaline NaBH

4solutions in presence

of CoB-1 catalyst were carried out with two different pro-cedures The evaluated H

2volume versus time during the

reactions was given in Figure 5 The H2generation started

immediately after catalyst contact with alkaline NaBH4solu-

tion As a result of this CoB-1 catalyst did not have inductionperiod to be active Effect of increasing in temperature wasshown in Figure 5TheH

2evolution shows direct proportion

with temperature in both systems In sonochemical alkalineNaBH

4solution hydrolysis hydrolysis time dropped 140min

from 941min by increasing of temperature from 22∘C to60∘C The same tendency was observed in magnetic stirringhydrolysis and reaction time decreased to 1388min

Figure 6 shows the effects of temperature and sono-waves on hydrogen generation It was clearly seen that bycomparing two different approach sono-waves developed thehydrolysis characteristics of system via cavitation on surfaceof catalystThe ultrasonic approach improved the interactionbetween the Co-B catalyst and alkaline NaBH

4solution

and made homogeneous distribution in the alkaline NaBH4

6 Journal of Chemistry

0

2000

4000

6000

8000

10000

40 60 80

Alkaline hydrolysis

SonohydrolysisMagnetic stirring hydrolysis

Temperature (∘C)

H2

gene

ratio

n ra

te (H

2ca

t)minus1

minus1

mL

min

gNaBH4

Figure 6Hydrogen generation rate comparison versus temperaturefor sonohydrolysis and magnetic stirring hydrolysis of alkaline(10wt) 012 NaBH

4solutions in presence of 05mg CoB-1 catalyst

solution and CoB-1 catalyst During the sonohydrolysiscavitation bubbles created high energy effects and this causedcontinuous acceleration of hydrogen generation rate [19]As can be seen ultrasonic treatment during the hydrolysisresults in maximum increase in the hydrogen generationfrom alkaline NaBH

4solution up to 65 at 40∘CThe authors

suggest to use of sonohydrolysis instead of magnetic stirringhydrolysis for improving the hydrogen generation rate ofsystem

Figure 7 shows the kinetic investigation of sonochemi-cal and magnetic stirring hydrolysis in presence of CoB-1catalyst The characterization of hydrolysis reaction behaviorwas identified by zero-order first-order and second-orderreaction kinetic models and Arrhenius theory As seen fromFigure 7 in both hydrolysis conditions the hydrolyses ofalkaline NaBH

4solutions were in compliance with zero-

order reaction kineticmodel and this indicated that hydrogengeneration rate was independent from concentration ofNaBH

4 Depending onArrhenius theory activation energy of

sonohydrolysis of alkalineNaBH4solutionwas 4615 kJsdotmolminus1

and its Arrhenius rate constant was 1989minminus1 For hydrol-ysis of alkaline NaBH

4solution which was carried out in

magnetic stirring systems the kinetic valueswere determinedas 5168 kJsdotmolminus1 activation energy and 1516minminus1 Arrheniusrate constant

In literature Co containing catalysts activation ener-gies were determined and summarized in Table 3 Theactivation energies of Co containing catalysts show vari-ety for example Copowder (7500 kJsdotmolminus1) Co-Raneyform (5370 kJsdotmolminus1) and active carbon supported Co-B(5780 kJsdotmolminus1) were relatively higher than our results whileCo nanoparticle (3500 kJsdotmolminus1) was lowerThe hydrolysis ofalkaline NaBH

4solution was carried out with sonochemical

approach the reaction kinetic was improved and value ofthem was decreased up to 12

Table 3 Activation energies in presence of various Co-basedcatalysts

Catalyst Activation energy(kJsdotmolminus1) References

Co powder 7500 [31]

Co nanoparticle 3500 [13]

Co (120572-Al2O3 support) 3263 [32]

Co (Raney form) 5370 [33]

Co-B (active carbon support) 5780 [34]

Co-B powder 6487 [12]

Co-B (clay support) 5632 [35]

Co-B 5273 [36]

CoB-1 (sonohydrolysis) 4615 At thiswork

CoB-1 (magnetic stirringhydrolysis) 5168 At this

work

4 Conclusion

In the present study sonochemical approach to coprecipi-tation synthesis of Co-B catalyst and hydrolysis of alkalineNaBH

4solutions was introducedThe following points result

from this studyThe sono-co-precipitation of CoCl

2sdot6H2O and B

2O3in

aqueous solution at pH 6 was proven to be a promisingprocedure in order to obtain Co-B crystalline catalyst withuniform 125 120583m particle size improved surface area andtexture properties On the other hand it was found that sono-chemical approach did not affect the crystalline structure andspectral properties of Co-B catalyst yet

The improving effect of sonochemical process on hydrol-ysis of alkaline NaBH

4solutions was approved when it

was compared with magnetic stirring system kinetic resultsHydrogen generation rate of alkaline NaBH

4solutions via

sonohydrolysis method in presence of CoB-1 catalyst hasshown enhanced influence at all temperatures Activationenergy as 4615 kJsdotmolminus1 of sonochemical coprecipitationsynthesized Co-B catalyst has compatible value comparedwith literature (32ndash75 kJsdotmolminus1) Rate law was formulized asgiven below

119903NaBH4

= 1989 sdot 119890minus4615RT (9)

As a result of this study the ultrasonicwaves improved theintrinsic and extrinsic properties of Co-B catalyst propertiesas specific surface area increased up to 70 particle sizedecreased up to 58 and hydrogen generation rate increasedup to 64 As can be seen sonochemical coprecipitationand sonohydrolysis proved to be promising techniques forsynthesis of Co-B catalyst and hydrolysis

Journal of Chemistry 7

000

002

004

006

008

010

012

014

0 5 10 15 20Time (min)

Alkaline sonohydrolysis Zero-order reaction kinetic

000

100

200

300

400

500

0 5 10 15 20Time (min)

Alkaline sonohydrolysis First-order reaction kinetic

000

10000

20000

30000

40000

50000

60000

0 5 10 15 20Time (min)

Alkaline sonohydrolysis Second-order reaction kinetic

000

002

004

006

008

010

012

014

0 5 10 15 20Time (min)

Alkaline magnetic stirring hydrolysisZero-order reaction kinetic

000

100

200

300

400

500

0 5 10 15 20Time (min)

Alkaline magnetic stirring hydrolysisFirst-order reaction kinetic

000

10000

20000

30000

40000

50000

60000

0 5 10 15 20Time (min)

Alkaline magnetic stirring hydrolysisSecond-order reaction kinetic

Ln(C

CN

aBH

4)C

minusC

NaB

H4

(M)

Cminus

CN

aBH

4(M

)(1

CN

aBH

4)minus

(1C

)

22∘C

40∘C

60∘C

22∘C

40∘C

60∘C

NaBH4 NaBH4

NaBH4NaBH4

NaBH4 NaBH4

Ln(C

CN

aBH

4)

(1C

NaB

H4)minus

(1C

)

NaB

H4 0

NaB

H4 0

NaB

H4 0

NaB

H4 0

NaB

H4 0

NaB

H4 0

Figure 7The kinetic investigation the zero first and second reaction kinetic models for sonohydrolysis and magnetic stirring hydrolysis ofalkaline (10wt) 012M NaBH

4solutions

Symbols Used

119903 [H2molsdotminminus1sdotgminus1 cat] H

2generation rate

119864119886 [kJsdotmolminus1] Activation energy119877 [kJsdotmolminus1 sdot∘Cminus1] Gas constant119879 [∘C] Temperature

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgments

The authors would like to thank the Yildiz Technical Univer-sity Research Foundation (Project no 2012-07-01-YL02) forits financial support

References[1] S C Amendola S L Sharp-Goldman M S Janjua et al ldquoSafe

portable hydrogen gas generator using aqueous borohydridesolution and Ru catalystrdquo International Journal of HydrogenEnergy vol 25 no 10 pp 969ndash975 2000

8 Journal of Chemistry

[2] R Retnamma A Q Novais and C M Rangel ldquoKinetics ofhydrolysis of sodium borohydride for hydrogen productionin fuel cell applications a reviewrdquo International Journal ofHydrogen Energy vol 36 no 16 pp 9772ndash9790 2011

[3] O Akdim U B Demirci D Muller and P Miele ldquoCobalt(II) salts performing materials for generating hydrogen fromsodiumborohydriderdquo International Journal of Hydrogen Energyvol 34 no 6 pp 2631ndash2637 2009

[4] J Liang Y Li Y Huang et al ldquoSodium borohydride hydrolysison highly efficient Co-BPd catalystsrdquo International Journal ofHydrogen Energy vol 33 no 15 pp 4048ndash4054 2008

[5] U B Demirci O Akdim J Andrieux J Hannauer RChamoun and P Miele ldquoSodium borohydride hydrolysis ashydrogen generator Issues state of the art and applicabilityupstream froma fuel cellrdquo Fuel Cells vol 10 no 3 pp 335ndash3502010

[6] US Department of Energy Hydrogen Program 2007httpwwwhydrogenenergygov

[7] U B Demirci and P Miele ldquoSodium borohydride versusammonia borane in hydrogen storage and direct fuel cellapplicationsrdquo Energy and Environmental Science vol 2 no 6pp 627ndash637 2009

[8] B H Liu and Z P Li ldquoA review Hydrogen generation fromborohydride hydrolysis reactionrdquo Journal of Power Sources vol187 no 2 pp 527ndash534 2009

[9] S Cavaliere J Hannauer U B Demirci O Akdim and PMieleldquoEx situ characterization of N

2H4- NaBH

4- and NH

3BH3-

reduced cobalt catalysts used in NaBH4hydrolysisrdquo Catalysis

Today vol 170 no 1 pp 3ndash12 2011[10] H I Schlesinger E R Brown A E Finholitam J R Gilbreathh

H R Hoekstra and E A Hyde ldquoProcedures for the preparationof methyl boraterdquo Journal of American Chemical Society vol 75no 1 pp 213ndash215 1953

[11] A M Ozerova V I Simagina O V Komova et al ldquoCobaltborate catalysts for hydrogen production via hydrolysis ofsodium borohydriderdquo Journal of Alloys and Compounds vol513 pp 266ndash272 2012

[12] S U Jeong R K Kim E A Cho et al ldquoA study on hydrogengeneration from NaBH

4solution using the high-performance

Co-B catalystrdquo Journal of Power Sources vol 144 no 1 pp 129ndash134 2005

[13] R Khan S W Kim T-J Kim and C-M Nam ldquoComparativestudy of the photocatalytic performance of boron-iron Co-doped and boron-doped TiO

2nanoparticlesrdquoMaterials Chem-

istry and Physics vol 112 no 1 pp 167ndash172 2008[14] A Kanturk Figen and B Coskuner ldquoA novel perspective for

hydrogen generation from ammonia borane (NH3BH3) with

Co-B catalysts lsquoultrasonic Hydrolysisrsquordquo International Journal ofHydrogen Energy vol 38 no 6 pp 2824ndash2835 2013

[15] C C Yang M S Chen and Y W Chen ldquoHydrogen generationby hydrolysis of sodium borohydride on CoBSiO

2catalystrdquo

International Journal ofHydrogenEnergy vol 36 no 2 pp 1418ndash1423 2011

[16] R Patil P Bhoir P Deshpande T Wattamwar M Shirude andP Chaskar ldquoRelevance of sonochemistry or ultrasound (US)as a proficient means for the synthesis of fused heterocyclesrdquoUltrasonics Sonochemistry vol 20 no 6 pp 1327ndash1336 2013

[17] T Q Liu O Sakurai N Mizutani and M Kato ldquoPreparationof spherical fine ZnO particles by the spray pyrolysis methodusing ultrasonic atomization techniquesrdquo Journal of MaterialsScience vol 21 no 10 pp 3698ndash3702 1986

[18] S L Che K Takada K Takashima O Sakurai K Shinozakiand N Mizutani ldquoPreparation of dense spherical Ni particlesand hollow NiO particles by spray pyrolysisrdquo Journal of Materi-als Science vol 34 no 6 pp 1313ndash1318 1999

[19] C L Bianchi E Gotti L Toscano and V Ragaini ldquoPreparationof PdC catalysts via ultrasound a study of the metal distribu-tionrdquo Ultrasonics Sonochemistry vol 4 no 4 pp 317ndash320 1997

[20] S S Ostapenko L Jastrzebski J Lagowski and B SoporildquoIncreasing short minority carrier diffusion lengths in solar-grade polycrystalline silicon by ultrasound treatmentrdquo AppliedPhysics Letters vol 65 no 12 pp 1555ndash1557 1994

[21] M Run SWu andGWu ldquoUltrasonic synthesis ofmesoporousmolecular sieverdquo Microporous and Mesoporous Materials vol74 no 1-3 pp 37ndash47 2004

[22] U R Pillai E Sahle-Demessie and R S Varma ldquoAlterna-tive routes for catalyst preparation use of ultrasound andmicrowave irradiation for the preparation of vanadium phos-phorus oxide catalyst and their activity for hydrocarbon oxida-tionrdquo Applied Catalysis A General vol 252 no 1 pp 1ndash8 2003

[23] H LiH Li J ZhangWDai andMQiao ldquoUltrasound-assistedpreparation of a highly active and selective Co-B amorphousalloy catalyst in uniform spherical nanoparticlesrdquo Journal ofCatalysis vol 246 no 2 pp 301ndash307 2007

[24] M G Sulman ldquoEffects of ultrasound on catalytic processesrdquoRussian Chemical Reviews vol 69 no 2 pp 165ndash177 2000

[25] H Li J Zhang and H Li ldquoUltrasound-assisted preparationof a novel Ni-B amorphous catalyst in uniform nanoparticlesfor p-chloronitrobenzene hydrogenationrdquo Catalysis Communi-cations vol 8 no 12 pp 2212ndash2216 2007

[26] A J Hung S F Tsai Y Y Hsu J R Ku Y H Chen and CC Yu ldquoKinetics of sodium borohydride hydrolysis reaction forhydrogen generationrdquo International Journal ofHydrogen Energyvol 33 no 21 pp 6205ndash6215 2008

[27] O Levenspiel Chemical Reaction Engineering John Wiley ampSons New York NY USA 3rd edition 1999

[28] L Jun X Shuping and G Shiyang ldquoFT-IR and Ramanspectroscopic study of hydrated boratesrdquo Spectrochimica ActaA Molecular Spectroscopy vol 51 no 4 pp 519ndash532 1995

[29] A Kanturk M Sari and S Piskin ldquoSynthesis crystal structureand dehydration kinetics of NaB(OH)

4sdot2H2Ordquo Korean Journal

of Chemical Engineering vol 25 no 6 pp 1331ndash1337 2008[30] Q Zhang Y Wu X Sun and J Ortega ldquoKinetics of catalytic

hydrolysis of stabilized sodium borohydride solutionsrdquo Indus-trial and Engineering Chemistry Research vol 46 no 4 pp1120ndash1124 2007

[31] J Andrieux D Swierczynski L Laversenne et al ldquoAmultifactorstudy of catalyzed hydrolysis of solidNaBH

4on cobalt nanopar-

ticles thermodynamics and kineticsrdquo International Journal ofHydrogen Energy vol 34 no 2 pp 938ndash951 2009

[32] B H Liu Z P Li and S Suda ldquoNickel- and cobalt-basedcatalysts for hydrogen generation by hydrolysis of borohydriderdquoJournal of Alloys and Compounds vol 415 no 1-2 pp 288ndash2932006

[33] W Ye H Zhang D Xu L Ma and B Yi ldquoHydrogen generationutilizing alkaline sodium borohydride solution and supportedcobalt catalystrdquo Journal of Power Sources vol 164 no 2 pp 544ndash548 2007

[34] J Zhao H Ma and J Chen ldquoImproved hydrogen generationfrom alkaline image solution using carbon-supported image ascatalystsrdquo International Journal of Hydrogen Energy vol 32 no18 pp 4711ndash4716 2007

Journal of Chemistry 9

[35] H Tian Q Guo and D Xu ldquoHydrogen generation fromcatalytic hydrolysis of alkaline sodium borohydride solutionusing attapulgite clay-supported Co-B catalystrdquo Journal ofPower Sources vol 195 no 8 pp 2136ndash2142 2010

[36] C H Liu B H Chen C L Hsueh J R Ku M S Jeng and FTsau ldquoHydrogen generation from hydrolysis of sodium boro-hydride using Ni-Ru nanocomposite as catalystsrdquo InternationalJournal of Hydrogen Energy vol 34 no 5 pp 2153ndash2163 2009

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